The supplements - bird flu debate: selenium

Following last week's claims and counter claims that dietary
supplements may offer protection from avian flu, Stephen
Daniells looks into statements that selenium supplements may
offer protection.

Many novel virus have been found in selenium deficient populations,
with experts suggesting that relatively harmless viruses can mutate
into deadly versions on passing through a selenium deficient host.

This has led some to propose that selenium supplements may offer
some kind of protection from the world's newest threat - avian
'flu.

Consumers seem to be taking notice of such reports, with some
companies reporting increased sales in light of increased press
coverage.

Rita Stoffaneller, senior nutritionist and registrations manager
with Wassen International Ltd who offer a range of selenium
products, told NutraIngredients.com​: "Consumers are
increasingly aware of the role of selenium and immune protection.
Recent press articles have generated a sales increase of more than
60% across the range in the UK in the last 2 weeks."​

The link between selenium and immune system health is backed up
by a growing body of science.

Researchers from the University of North Carolina, and the US
Department of Agriculture reported that selenium deficient mice
infected with a mild strain of influenza developed severe lung
infections. When the researchers recovered the virus from the mice,
they found an increased number of viral mutations, "resulting in
a more virulent phenotype."​ (Trends in Microbiology​,
2004, Vol. 12, pp. 417-423).

"Wide-spread nutritional deficiencies occur in many
developing countries, which are frequently the site of emergence of
new viral diseases as well as old viral diseases with new
pathogenic properties,"​ wrote the researcher.

The increased occurrence of mutated viruses in
selenium-deficient individuals has been linked to the antioxidant
nature of the mineral. Selenium is included into about 25
selenoproteins, five of which are powerful antioxidant enzymes.

If the host's antioxidant defences are weakened, then the virus
is exposed to greater oxidative stress, and thus a greater chance
of viral mutations.

Not only have low selenium levels been linked to higher virus
mutations, but also to a reduction in the efficiency of the immune
system. Selenium deficiency has been linked to reduced T-lymphocyte
activity and reduced antibody production.

Dr Margaret Rayman of the Centre of Food Safety and Nutrition at
Surrey University has published several articles on the immune
boosting activities of selenium (Proceedings of the Nutrition
Society​, 2002, Vol. 61,pp. 203-215).

"Taking a selenium supplement may make a difference to a
person with low selenium status and may help them deal more quickly
and effectively with a viral infection. This could reduce their
chances of becoming seriously ill,"​ said Rayman.

It would be incorrect and irresponsible to suggest that
increasing the selenium intake of populations will eradicate the
threat of H5N1. However, like vitamin C and zinc, the mineral could
boost the body's natural defences, a view shared by Wassens.

The US Council for Responsible Nutrition recently warned
consumers to be wary of supplements being touted as offering
protection from avian flu.

In a statement issued in November, the CRN said: "We do not
believe that any dietary supplements have been specifically shown
to prevent or treat avian 'flu."​

Judy Blatman, VP communications for CRN told
NutraIngredients-USA.com at that time: "We believe that
responsible supplement companies will not take advantage of
consumers' fears about avian flu and try and market a product as a
remedy for it."​

European selenium levels have been falling since the EU imposed
levies on wheat imports from the US, where soil selenium levels are
high. As a result, average intake of selenium in the UK has fallen
from 60 to 34 micrograms per day.

The European recommended daily intake (RDI) is 65
micrograms.

The current market for selenium supplements in Europe is
estimated to be worth around €40 million.